a. Field of the Invention
The present invention pertains generally to heating and insulation and more particularly to warm window systems.
b. Description of the Background
Warm window systems using tin oxide coatings have existed for a number of years. These systems operate by applying an electrical signal across the surface of tin oxide coated glass. The resistive qualities of the tin oxide create heat in response to the electric current that warms the window pane. A typical warm window system is disclosed by Prelco at Prelco website. The Prelco website discloses many of the advantages of warm window systems.
Application of electrical current to the tin oxide coating is normally made through a buss bar connection. Typical buss bar connections are made using copper strips that are connected to the tin oxide layer using an adhesive or by silk screening of the buss bar. Adhesive copper strips are only able to carry low currents and easily delaminate. Silk screening processes are not well adapted to low cost and high volume manufacturing. Silk screening is a multi-step process and must be done on the individual plates of glass after they have been coated with the tin oxide layers. The process is slow and awkward and require time consuming curing processes.
Some buss bar connections are made through high temperature deposition techniques. These techniques require that the tin oxide coated glass be subjected to the high temperature deposition technique. As a result, tempered or heat strengthened glass must be used to prevent breakage. Less expensive annealed and/or laminated glass cannot be used in this type of process because high heat differentials during deposition of the buss bar cause the glass to break. In addition, the entire pane of glass must be subjected to this process, which is awkward and results in expensive fabrication processes.